Chlorination Threat?

The more that scientists learn about man-made chemicals in the environment, the greater the dangers to public health seem to be. Indeed most specialists in the new field of environmental disease believe that 85% of all cancers are caused by exposure to substances in the air or water. These include everything from compounds in tobacco and automotive fumes to asbestos, vinyl chloride, the pesticide dieldrin, carbon tetrachloride and chloroform.

Now there is a new threat. Paradoxically, it involves chlorination, the process that most U.S. towns and cities use to kill the disease-carrying bacteria in ordinary drinking water. When water from a polluted source, like Lake Erie or the Mississippi River, enters a treatment plant, the chlorine apparently interacts with industrial and agricultural wastes to produce chemical compounds that have been shown to cause cancer in laboratory animals.

Concern arose last year when the Environmental Protection Agency's Cincinnati laboratory found that the levels of some hazardous chemicals in polluted water--most notably carbon tetrachloride and chloroform--increased when passed through municipal water-treatment plants.

Why? The EPA found in later tests that New Orleans' drinking water, which comes from the Mississippi River, contained minute traces of 66 organic chemicals, some of them known carcinogens. (In New Orleans last week, there was a rush on bottled water, and city officials announced that they would investigate the water supply further.) Actually, the link between chlorination and the formation of these chemicals was confirmed abroad. J.J. Rook, a Dutch scientist, added chlorine to contaminated river water and to relatively pure lake water. The concentration of carbon tetrachloride and chloroform rose sharply in the polluted water, but not in the sample from the lake.

Meantime, the Environmental Defense Fund, a public interest group of scientists and lawyers, was approaching the problem from a different angle. A research team compared statistics on the mortality rate of cancers of the urinary organs and gastrointestinal tract in 64 Louisiana parishes (counties). The study showed a "significant relationship" between the use of drinking water from the Mississippi and cancer deaths. The report also noted that dangerous chemicals had been identified in municipal drinking-water supplies in West Virginia, Indiana, Ohio, Nebraska and Washington, D.C.

More Study. The EPA quickly responded by ordering a two-part nationwide study of drinking-water supplies. The first phase will determine the concentration and potential effects of the various chemicals in U.S. drinking-water systems. After that, the possible sources of pollutants--mainly industrial discharges and agricultural runoffs --will be investigated, along with ways to eliminate them either at their source or in water-treatment plants.

This week the U.S. House of Representatives will consider a bill to set strict minimum national standards for drinking water A new item certain to be on the agenda for discussion, the possible hazards of chlorination.

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